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right then

im currently working as a electricians mate with quite a big firm, im 31 and in the job for just short of a year now, im in the middle of my 2330 course and im really stuck on pottential difference. hopefully somebody can help me out :)

ok so i understand that if you put your tester across phase and neutral of a ceiling rose lets say the pd is 230v, i get that but what im not getting is how the voltage is there?

i dunno if im making sense on this, its hard to explain something you dont no about lol.

il try again, we were told at college that the voltage kind of pushes the current through a circuit, so from the consumer unit does the voltage travel down the live conductor or am well off the mark there?

hopefully somebody can clear this up for me

many thanks
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  • Thread Starter Thread Starter
  • #2
pd, or potential difference really describes itself.

if you have two electrical points in a circuit, and they each have a potential on them, then the difference between them is the potential difference

i use the term WRT, which is 'with respect to'

so in a domestic circuit, the neutral condcutor is at 0V, the line conductor is at 230V with respect to it. If you measured between two 230V points on the same phase, you would measure no voltage, because there is no difference in potential there

your ignition warning light in your car works like this, when you start up there is 12V one side and 0V the other, so the lamp lights. When the car is running the alternator puts about 13V on both sides of the lamp and there is no potential difference, so the lamp goes out, there is still a voltage there, but no POTENTIAL DIFFERENCE

in your house, all of the line conductors are at 230V with respect to all of the neutral conductors, which are at 0V.

when you connect anything between them (ie lamp) this has 230V applied ACROSS it, and so draws a current THROUGH it

that make any sense???:rolleyes:


  • Thread Starter Thread Starter
  • #3
hi tony

thanks a lot for your reply and such a good way of getting the point across, just to clarify on one thing the line is set at 230v from the substation so in theory when you connect your consumer unit up and turn it on there is 230v through the line conductor.

thanks again for your reply


  • Thread Starter Thread Starter
  • #4

you got it:D

there is always an element of voltage drop depending on current draw. But you can take your line conductors as being a nominal 230V throughout the system

this is certainly the figure you will use for any calculations
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